(57) An oscillator circuit having a source of an oscillating signal, a tank circuit including
an inductor (18, 420, 421) and a capacitor (18, 420, 421), and a discretely switchable
capacitance module (14, 314) configured to control an amount of capacitance in the
oscillator circuit. The discretely switchable capacitance module (14, 314) includes,
a capacitor (22, 322) coupled between a first node (41, 341) and a second node (42,
342), a switch (24, 320) coupled between the second node (42, 322) and a third node
(43, 343); and a DC feed circuit (28, 328, 329), having a first end (28a, 328a, 329a)
coupled to the second node (42) and a second end (28b, 328b, 329b) configured to receive
a first or second control signal (30, 330). The control node (25, 325) of the switch
(24, 320) is tied to a predetermined bias voltage (26, 326). When the first control
signal (30, 330) is applied, the capacitor (22) is coupled between the first node
(41, 341) and the third node (43, 343) via the switch (24, 320), and when the second
control signal (30, 330) is applied the capacitor (22) is decoupled from the inductor
(18, 420, 421).
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